Advances in semiconductor processing and logic design have permitted an increase in the amount of logic that may be present on integrated circuit devices. As a result, computer system configurations have evolved from multiple integrated circuits in a system to multiple hardware threads, multiple cores, multiple devices, and/or complete systems on an individual integrated circuit. As the density of integrated circuits has grown, the power requirements for computing systems (from embedded systems to high performance computing (HPC) systems) have also escalated.
Power and thermal management issues are considerations in designing computer-based systems. In HPC systems, for example, a specified thermal design power (TDP) and/or the cost of electricity may drive the need for low power systems. In other systems, including mobile systems, battery life and thermal limitations make these issues relevant. Optimizing a system for maximum performance at minimum power consumption is usually done using the operating system (OS) or system software to control hardware elements.
Some models for power and thermal control may monitor the running average power of a hardware device over a relatively large and dynamically adjustable window of time and maintain this average power at or below a given threshold. Such an approach may enable the device to consume above-limit power for short durations (as long as the running average power remains within the limit), but the device power supply and cooling solution put limits on the magnitude and length of the excursion.